You might be carrying a bacteria that will attack you once you are hospitalized

The shocking mice experiment

The researchers were testing catheters on mice and discovered that urinary tract infections (UTIs) emerged in mice's bodies soon after the experiment. Catheters are sterile (bacteria-free) tubes that are inserted in a patient’s body before surgery to drain out the urine stored in his or her bladder. 

Surprisingly, soon after the mice experiment, Acinetobacter baumannii, a gram-negative bacteria that cause UTIs, lung infections, and various other health issues in humans, emerged and started multiplying in the mice's bodies. 

No trace of A. baumannii was found in the mice bladder before the experiment. The catheter was also free from any bacteria. Still, the mice developed an infection because the bacteria was actually hiding inside the mice’s bladder cells.  

The study authors believe hospitalized human patients who are supposed to undergo surgery could also get deadly bacterial infections in the same way as the mice. Therefore, it is important to screen a patient for any such bacteria before surgery because no matter how clean or sterile the hospital is —- You can’t prevent patients from catching deadly infections from themselves.  

One of the study authors and a professor at WUSTL, Mario Feldman, said, “This study shows that patients may be unwittingly carrying the bacteria into the hospital themselves, and that has implications for infection control."

He further added, "If someone has a planned surgery and is going to be catheterized, we could try to determine whether the patient is carrying the bacteria and cure that person of it before the surgery. Ideally, that would reduce the chances of developing one of these life-threatening infections.”

Validating the risk from A. baumannii

Escherichia coli is the bacteria that causes UTIs in healthy individuals. Previous studies have shown that this bacteria can stay hidden in the gut or bladder cells in humans and cause recurring UTIs and other infections. In order to check if A. baumannii could do the same, the researchers decided to study mice with weak immunity and UTIs.

They didn’t include mice with strong immunity in their research because, similar to healthy humans, such mice won’t be affected by A. baumannii. After the mice recovered from the UTIs, the researchers examined their urine for two months and didn’t find any bacteria. 

In the next phase, they performed they inserted sterile catheters inside mice, and interestingly, in just 24 hours of this experiment, UTIs emerged in 50 percent of the catheterized mice population. These infections were the same as the infections previously caused by A. baumannii and confirmed the bacteria’s presence inside mice's bladder cells.

Explaining this further, study author and UTI expert Scott J. Hultgren said, “The bacteria must have been there all along, hiding inside bladder cells until the catheter was introduced. Catheterization induces inflammation, and inflammation causes the reservoir to activate, and the infection blooms.”

The authors suggest that it is possible many people are already carrying A. baumannii in their bodies. There won’t be any problem as long as they are healthy. However, once they fall sick and are hospitalized, the bacteria could get a chance to multiply, spread infection, and put patients’ lives in danger. 

Moreover, such bacteria are highly-resistant to antibiotics which makes it difficult to control their infection in patients who have weak immunity. Therefore, it is very important to prevent any such deadly infections by screening patients who are admitted for specific types of treatments) beforehand. 

The researchers look forward to finding more such bacteria and the medical procedures that trigger them. Hopefully, these findings will be useful in improving infection-control measures in hospitals in the US and across the globe.  

The study is published in the journal Science Translational Medicine.